gpsd service does not locate USB GPS

Question

I have a BU-353S4 USB GPS receiver. I am running Kubuntu 18.04. When I manually run gpsd with gpsd /dev/ttyUSB0, it correctly identifies the device and gets a fix when one is available.

When I let gpsd run automatically, this doesn't work. It seems that gpsd does not find the device and does not try to open it.

If I add /dev/ttyUSB0 to /etc/defaults/gpsd and I run the service, then the GPS works. However, if I then disconnect the GPS and reconnects it, then the daemon does not locate it again.

My /etc/defaults/gpsd says:

# Default settings for the gpsd init script and the hotplug wrapper.

# Start the gpsd daemon automatically at boot time
START_DAEMON="true"

# Use USB hotplugging to add new USB devices automatically to the daemon
USBAUTO="true"

# Devices gpsd should collect to at boot time.
# They need to be read/writeable, either by user gpsd or the group dialout.
DEVICES="/dev/ttyUSB0"

# Other options you want to pass to gpsd
GPSD_OPTIONS=""

What am I doing wrong?